1. Field of the Invention
This invention relates to vehicle safety equipment. More particularly, the invention relates to a metal bladder which is inflated by a gas generator when the vehicle is struck with excessive force.
2. Description of the Related Art
Front mounted air bags that inflate in an automobile collision are mounted in the steering wheel column, the glove box or the dashboard of many motorized vehicles. In the event of a front end collision, the air bags are inflated by a gas and substantially fill that portion of the passenger compartment not occupied by the driver or a passenger. The combination of a seat belt and an air bag is effective to restrain an automobile passenger in the event of a front end collision, minimizing the likelihood of severe injury.
Front mounted air bags, while highly effective for front end collisions, are less effective for side impact collisions and collisions occurring at more than 30.degree. from a front end collision. Accordingly, there is a need to provide automobiles with air bags effective to restrain a passenger in a side impact collision.
U.S. Pat. No. 5,308,112 to Hill et al. discloses a fabric air bag for side impact collisions. The air bag is mounted within a door panel in an unfurled, deflated position. The unfurled bag deploys more quickly and provides more reliable orientation than air bags stored in a rolled, furled or coiled state.
U.S. Pat. No. 5,316,336 to Taguchi et al. discloses a rubber or fabric air bag for providing passenger restraint in the event of a side impact collision. The air bag is mounted in a door panel above a gas generator. On impact, the bag is unfurled and extends laterally upward along the inside of the door. The orientation of the air bag relative to the gas generator provides more efficient use of generated gas and more rapid inflation of the air bag.
The rate of deployment of a fabric or rubber air bag is limited. These flexible fabric bags can not tolerate high inflation gas temperatures. At higher temperatures the bag may burn, exposing the passengers to hot gas.
Fabric air bags are also designed to vent gases into the vehicle interior. Therefore, the chemical composition of the gas generator used to inflate the air bag must be limited to compositions that generate non-toxic gases at relatively low temperature. The gas stream further may not contain excessive amounts of solid particles or flammable gases.
The flexibility of fabric air bags is a detriment. The air bags must be precisely folded or supported in a specific orientation to ensure rapid deployment. Over extended periods of time, as the automobile is subject to the bumps and centrifugal force of normal driving, it is possible for the flexible air bag to shift position and effective deployment of the air bag impaired.
Another method to protect the occupants in a collision is the use of energy absorbing structural components mounted in hollow sections of the automobile such as inside the door panel, under the hood or in the trunk adjacent to the bumper.
U.S. Pat. No. 3,888,502 discloses energy absorbing components for an automobile. Hollow drawn or spot welded tubes are filled with plastic beads and inserted into the walls of the automobile. The plastic beads absorb impact energy and cause a more uniform, controlled collapse of the hollow members.
U.S. Pat. No. 4,050,537 to Bez, discloses a hollow metallic member installed within an automobile wall. On impact, the hollow member is pressurized, typically by an explosive charge, deforming the walls of the hollow metallic member outward to increase resistance to buckling.
These structural elements, while effective, are of limited value. The polymer beads have a volumetric weight of 75-150 kg/m.sup.3 and contribute undesirable weight to the automobile. Structural members that can withstand an explosion without bursting must be carefully designed and protected from corrosion, heat and other strength reducing conditions.
The above problems with both side impact air bags and internal structural members are solved by the use of an inflatable metal bladder. Inflatable metal bladders to disperse munitions have been disclosed in U.S. Pat. No. 5,107,767 to Schneider et al. However, that patent is oriented toward providing propulsive forces to propel munitions and does not suggest mechanisms under which metallic bladders may be used to restrain or otherwise protect an automobile passenger.
There remains a need for an air bag assembly utilizing an inflatable metal bladder that does not suffer from the problems of the prior art.